The present invention relates to a heat pump air conditioning system for a vehicle which has improved heating performance and effectively heats a passenger compartment even when an outside air temperature is low and a vehicle speed is high.
As a heat pump air conditioning system for vehicles, Japanese Patent Laid-Open Publication No. SHO-60-76414 xe2x80x9cAIR CONDITIONER FOR VEHICLExe2x80x9d, for example, is known. This air conditioner is shown in FIG. 8 hereof.
The conventional air conditioner shown in FIG. 8 consists of a compressor 102 driven by a subengine 101, an inside heat exchanger 104 for heat radiation and condensation of a high-temperature, high-pressure refrigerant gas flowing thereinto from the compressor 102 via a four-way valve 103 during heating, a heating expansion valve 106 connected to the inside heat exchanger 104 via a receiver 105, and an outside heat exchanger 107 for evaporation and heat absorption of the refrigerant gas throttled and expanded by the heating expansion valve 106. The refrigerant gas is returned from the outside heat exchanger 107 through the four-way valve 103 into the compressor 102.
A radiator fan 112 is mounted on the drive shaft of the subengine 101 via a gear unit 111. Changing the engagement of gears in the gear unit 111 causes the rotation direction of the radiator fan 112 to switch between the forward direction and the reverse direction. Specifically, when the outside air temperature is low and the heating performance is insufficient, the gear unit 111 usually switches the rotation direction of the radiator fan 112 to cause air flowing in the direction of arrow A to flow in the direction of arrow B, guiding the air heated around the engine to the outside heat exchanger 107 so that the outside heat exchanger 107 can effectively absorb the heat.
In the above air conditioner, when the vehicle travels at a high speed, the running wind cancels the flow of air in the direction of arrow B caused by the radiator fan 112, preventing the supply of heated air around the engine to the outside heat exchanger 107 and preventing effective heat absorption, and lowering heating performance.
It is thus desired to improve heat pump air conditioning systems for vehicles, increasing heating performances even with low outside air temperatures and high vehicle speeds, and thereby effectively heating the passenger compartments.
According to an aspect of the present invention, there is provided a heat pump air conditioning system for heating and cooling the passenger compartment of a vehicle, which system comprises: an inside heat exchanger disposed in the passenger compartment; an outside heat exchanger disposed in an engine compartment; refrigerant passages connecting the inside heat exchanger and the outside heat exchanger and charged with a refrigerant; and a compressor for compressing a refrigerant gas in the refrigerant passages; the outside heat exchanger comprising: a first outside heat exchanger disposed forward of an engine in the engine compartment to act as a heat radiator in cooling; and a second outside heat exchanger disposed in the vicinity of the engine in the engine compartment to act as a heat absorber in heating, utilizing the heat of the engine.
That is, since the second outside heat exchanger is operated as a heat absorber in heating, using the heat of the engine, the second outside heat exchanger can be prevented from being frosted even when the outside air temperature is low and the vehicle travels at a high speed. The engine waste heat can thus be efficiently absorbed, increasing the heating performance and allowing effective heating of the interior. Cooling can also be performed at the first outside heat exchanger as in the conventional manner.
Preferably, the second outside heat exchanger is provided with a fan for guiding air within the engine compartment thereto. That is, the fan can forcibly guide heated air inside the engine compartment to the second outside heat exchanger, increasing the degree of freedom in the installation location of the second outside heat exchanger in the engine compartment, and also increasing the heating effects.